At Eden camp a few years back they had a tunnel section built that you could go through. It was the same size and what a job it was getting through a small section. It was horrible very claustrophobic so, I cannot begin to imagine how scary it must have been working 30 feet underground in the heat and poor light with, a fall in a possibility at anytime in a tunnel you could just about move in. and, to top it off the germans trying to stop you.
Must have been really brave to have done such stuff
Mitch